For more information on brown ring patch, click

Steven J. McDonald, M.S.
Richard Grala
Bruce B. Clarke, Ph.D.
Reducing brown ring patch severity
on Poa annua greens
Brown ring patch is similar to other Rhizoctonia diseases, but does not react the same
way to fungicides.
Symptoms of brown ring patch start as small yellow rings with green grass in the center
and can ultimately reach a few feet in diameter. The yellow rings can turn an orange or brown color as the
disease progresses, and the pathogen may eventually kill affected turf. Photos by Steve McDonald
We have conducted joint research studies on the management of brown ring patch
since 2010. From a feld research perspective,
this disease has been challenging to work
with because it is diffcult to fnd naturally
infected putting greens with uniform disease incidence and severity. The main body
of research presented in this paper comes
from work conducted in 2010 and 2011 on
a putting green in New Jersey that exhibited
an unusually uniform distribution of brown
ring patch symptoms. Additional data were
obtained in 2012 and 2013 from smaller research trials on putting greens in Pennsylvania with less severe disease pressure. Brown
ring patch has become an important disease of annual bluegrass (Poa annua) putting greens in the Northeastern region of the
United States since 2007 (6).
The disease
Brown ring patch is caused by Waitea
circinata var. circinata (sometimes referred
to by its asexual stage R izoctonia circinata
var. circinata) and is a serious disease of
short-mowed annual bluegrass turf throughout much of the cool, humid regions of the
United States. In New Jersey and much of
the mid-Atlantic and Northeast regions, this
disease is often observed from early spring
— when annual bluegrass is breaking dormancy — through late spring. However, in
cooler regions, it can be a problem during the
summer when air temperatures range from
65 F to 95 F (18 C to 35 C). Although the
same pathogen can also signifcantly damage
roughstalk bluegrass (P. trivialis) and creeping bentgrass (Agrostis stolonifera) (4,6), our
86
GOLF COURSE MANAGEMENT 03.14
Fungicide products
Fungicide
Affirm 11.3WDG
Banner MAXX 1.3ME
Briskway 2.7SC
Fungicide group
Manufacturer
polyoxin-D
polyoxin
Nufarm/Cleary
propiconazole
DMI
Syngenta
azoxystrobin + difenoconzaole
QoI + DMI
Syngenta
Chipco 26GT 2SC
Chipco Signature 80WDG
Active ingredient
Study years†
2010
2011
C
C, P
C
iprodione
dicarboximide
Bayer
Aluminum-tris (fosetyl-AL)
phosphonate
Bayer
triticonazole
DMI
Bayer
thiophanate-methyl
benzimidazole
Nufarm/Cleary
C
C, P
chlorothalonil
chloronitrile
Syngenta
C
C, P
C
Chipco Triton Flo 3.1SC
Cleary 3336 4F
Daconil Ultrex 82.5WDG
Endorse 2.5WP
C
C, P
C, P
C
C, P
polyoxin-D
polyoxin
Arysta
Headway 1.39ME
azoxystrobin + propiconazole
QoI + DMI
Syngenta
Heritage TL 0.8ME
azoxystrobin
QoI
Syngenta
C
C, P
Medallion 50WP
fludioxonil
phenylpyrrole
Syngenta
C
C, P
Medallion 1SC
fludioxonil
phenylpyrrole
Syngenta
Pentathlon 4LF
mancozeb
dithiocarbamate
SePRO
ProStar 70WG
flutolanil
SDHI
Bayer
Secure 4.17SC
fluazinam
pyridinamine
Syngenta
Tartan 2.4SC
triadimefon + trifloxystrobin
DMI + QoI
Bayer
Torque 3.6SC
tebuconazole
DMI
Nufarm/Cleary
C, P
tebuconazole + polyoxin-D
DMI+ polyoxin
Nufarm/Cleary
P
penthiopyrad
SDHI
Syngenta
P
Velista 50WDG + Banner MAXX 1.3MEC
penthiopyrad + propiconazole
SDHI + DMI
Syngenta
P
Velista 50WDG + Daconil Ultrex 82.5WDG
penthiopyrad + chlorothalonil
SDHI + chloronitrile
Syngenta
P
Velista 50WDG + Heritage 50WDG
penthiopyrad + azoxystrobin
SDHI + QoI
Syngenta
P
Torque 3.6SC + Affirm 11.3WDG
Velista 50WDG
2013
C, P
C
C
C
C, P
C
C, P
C, P
C
C, P
†
Each fungicide was applied as curative (C) or preventive (P) in each trial year.
Table 1. Fungicides tested (in alphabetical order), their active ingredients and fungicide groups, and research sites.
research with this disease was conducted exclusively on annual bluegrass.
Symptoms of brown ring patch start as
small yellow rings (0.25-2 inches [0.635-5
centimeters] wide) with green grass in the
center and can ultimately reach a few feet
(>0.5 meter) in diameter. The yellow rings
can turn an orange or brown color as the disease progresses and, in some cases, the pathogen may eventually kill affected turf. After
a severe outbreak, the rings may be sunken,
are extremely slow to heal and can adversely
affect golf ball roll. In addition, rings of this
disease often appear as a series of smaller interconnected crescents, rather than the fairly
circular rings typically observed with yellow
patch (R izoctonia cereale), a pattern that can
often be used in the feld to distinguish between these similar diseases.
Because of the destructive nature of brown
ring patch, superintendents usually resort to
frequent fungicide applications to manage it.
In previous research, brown ring patch effcacy data from California, Virginia and Illinois demonstrated that there was variation in
fungicide control depending on the number
of applications made and whether treatments
were applied on a preventive or curative basis
(2). There have also been laboratory studies evaluating fungicide effectiveness, but
few feld fungicide effcacy trials have been
reported in the northeastern United States.
Furthermore, since brown ring patch has
only recently been recognized as a disease of
annual bluegrass turf, limited data are available about the impact of preventive and curative fungicide applications or the impact of
post-application irrigation on fungicide performance. Because the pathogen survives in
the lower canopy and thatch, fungicide placement may also affect disease control.
Earlier research
Researchers in California investigated
the impact of nitrogen fertilizer source and
the vegetative suppressant Primo MAXX
(trinexapac-ethyl, Syngenta) on the severity
of brown ring patch (5). Their research indicated that increasing fertilizer inputs (from
0.5 to 1.0 pound nitrogen/1,000 square feet
[2.4 to 4.8 grams/square meter]) reduced the
03.14 GOLF COURSE MANAGEMENT
87
solani), but their effect on brown ring patch
has only recently been evaluated.
Curative fungicide trial, 2010
Treatment No./name
Rate/1,000 square feet
% brown ring patch†
April 16
April 28
May 7
Curative treatments applied April 8, 2010
1. ProStar 70WP
2. Endorse 2.5WP
2.2 ounces
10.0 a‡
6.9 ab
14.0 bcd
0.9 ounce
7.2 a
8.0 ab
17.0 a-d
3. Heritage TL 0.8ME
2.0 fluid ounces
7.9 a
2.8 b
1.5 d
4. Banner MAXX 1.3ME
2.0 fluid ounces
11.9 a
24.4 a
32.3 ab
5. Cleary 3336 4FL
4.0 fluid ounces
5.9 a
12.7 ab
10.6 cd
3.25 ounces
9.3 a
19.1 ab
23.3 abc
6. Daconil Ultrex 82.5WDG
7. Chipco 26GT 2SC
4.0 fluid ounces
9.4 a
11.7 ab
13.3 bcd
8. Tartan 2.4SC
2.0 fluid ounces
10.8 a
6.8 ab
13.0 bcd
0.5 ounce
7.1 a
9.6 ab
8.6 cd
9. Medallion 50WP
10. ChipcoTriton Flo 3.1SC
11. Not treated
0.75 fluid ounce
7.8 a
6.9 ab
13.6 bcd
—
18.7 a
26.1 a
35.0 a
†
Percent plot area blighted by brown ring patch was rated on a scale of 0%-100%, where 0 = no disease and 100 =
entire plot area blighted.
‡
Means followed by the same letter are not signifcantly different from one another. Means were separated using Tukey’s
HSD test, P = 0.05.
Table 2. Impact of curative fungicide applications on brown ring patch disease on a predominantly annual bluegrass putting green at Fiddlers Elbow Country Club, Bedminster, N.J., 2010.
severity of brown ring patch, although this
has not typically been the case with other
R izoctonia diseases (3). Moreover, Primo
MAXX (5 fuid ounces/acre [0.365 liter/
hectare]) applied alone appeared to slightly
increase disease severity when compared to
the water control, but the combination of
Primo MAXX and nitrogen fertilizers had
no signifcant effect on the disease when
compared to nitrogen applications alone (5).
There have been no reports, however, on
the impact of other plant growth regulators
(PGRs) — such as Proxy (ethephon, Bayer)
or Embark (mefuidide, PBI-Gordon), which
are commonly used in spring to suppress annual bluegrass seedheads on greens — on this
disease.
Golf course superintendents maintaining predominately annual bluegrass putting
greens generally apply either Embark or a
tank mixture of Proxy and Primo MAXX
before seedhead formation is visible (in the
“boot” stage). This stage can be identifed by
examining the base of the stems of annual
bluegrass for swelling or bulging. A change
in the stem base indicates that seedheads
have begun to form. Seedhead suppressants
are most effective when applied just before
88
GOLF COURSE MANAGEMENT 03.14
or at the time of swelling (1). Applying these
PGRs several days after swelling has occurred
or when seedheads are visible is generally
less effective (1). Field observations suggest
that outbreaks of brown ring patch may be
enhanced by applications of these products;
however, there are currently no reports in the
literature to support this hypothesis.
Our research
The objectives of our research were to
evaluate classes of fungicides commonly used
on turf for their ability to control brown ring
patch on a preventive or curative basis, to assess the impact of post-application irrigation
on fungicide effcacy and to determine the
impact of selected PGRs on disease severity. Two fungicides, Velista (penthiopyrad,
Syngenta) and Secure (fuazinam, Syngenta),
were still experimental materials when they
were evaluated in our studies. Velista, which
belongs to the carboxamide (succinate dehydrogenase inhibitor; SDHI) class of fungicides, is expected to reach the turfgrass market in 2014; and Secure, a contact fungicide,
was brought to market in 2012. Both of these
chemistries provide good to excellent control of brown patch (caused by R izoctonia
2010, 2011 and 2013 fungicide trials
General materials and me ds
All of the fungicides, active ingredients,
fungicide groups, manufacturers and application timings used in this study are outlined in Table 1. Our two main brown ring
patch fungicide trials were conducted on the
11th green of the Meadow Course at Fiddlers
Elbow Country Club in Bedminster, N.J.
Turf consisted of a mixed annual bluegrass
and creeping bentgrass (70:30, respectively)
putting green mowed at 0.125 inch (3.2 millimeters) fve days per week with a triplex
reel mower. Extremely severe and uniform
symptoms of brown ring patch had been observed on this green for approximately six
years before our study, even though the superintendent had applied fungicides for control. Our treatments were applied in a water
carrier volume of 2 gallons/1,000 square feet
(81.5 milliliters/square meter) using a CO2pressurized boom at 38 psi (262 kpa) with
8008 EVS fat-fan nozzles. Treatment rates
and application dates are shown in Tables 2
and 3. Plots were 5 feet × 5 feet (1.5 meters ×
1.5 meters) and were replicated four times in
a randomized complete block design. A different location of the green was used for each
study. Plots were visually rated for percent
symptomatic turf on a scale of 0% to 100%,
where 0 = no symptoms and 100 = entire plot
area blighted. Disease control was considered
commercially acceptable if less than 5% of
the turf area was blighted.
Methods specific to the 2010
curative fungicide efficacy study
The entire green was treated with the PGR
(seedhead suppressant) Embark at 22.5 fuid
ounces/acre (1.64 liters/hectare) on April 2
and 3 (total of 45 fuid ounces/acre [3.28 liters/hectare]). All fungicide treatments were
applied once to a dry canopy on April 8, 2010.
2010 curative fungicide results
Brown ring patch severity was low
(<10%) at the initiation of the study, but the
disease was uniformly distributed throughout the trial area. It’s important to note that
the objective was to evaluate the effect of a
single “early-curative” fungicide application
on this disease. Most fungicides slowly reduced symptom severity over the study pe-
% brown ring patch, 2011
Treatment No./name
Rate/1,000 square feet
% brown ring patch†
April 25
May 2
May 11
Preventive treatments applied March 22, April 11 and April 25, 2011
1. ProStar 70WP
2.2 ounces
1.00 cd‡
3.9 cd
2.5 cd
2. Affirm 11.3WDG
0.9 ounce
0.00 d
4.5 cd
4.3 cd
3. Heritage TL 0.8ME
2.0 fluid ounces
3.00 cd
3.5 cd
3.3 cd
4. Banner MAXX 1.3ME
2.0 fluid ounces
1.25 cd
14.5 bcd
15.5 cd
5. Cleary 3336 4FL
4.0 fluid ounces
37.3 ab
46.5 a
56.5 a
3.25 ounces
5.0 bcd
7.3 bcd
7.3cd
7. Chipco 26 GT 2SC
4.0 fluid ounces
22.8a-d
27.3 a-d
28.8 a-d
8. Tartan 2.4SC
2.0 fluid ounces
6.3 bcd
7.0 bcd
7.0 cd
0.5 ounce
3.3 cd
4.5 cd
4.5 cd
6. Daconil Ultrex 82.5WDG
9. Medallion 50WP
10. Chipco Triton Flo 3.1SC
0.75 fluid ounce
2.3 cd
3.3 cd
4.0 cd
11. Torque 3.6SC
0.9 fluid ounce
5.0 bcd
5.3 cd
6.0 cd
12. Pentathlon 4LF
10.0 fluid ounces
5.3 bcd
8.3 bcd
9.5 cd
6.0 ounces
14.8 a-d
20.8 a-d
22.5 bcd
0.5 ounce + 3.25 ounces
9.8 bcd
10.8 bcd
9.5 cd
0.5 ounce + 1.0 fluid ounce
8.5 bcd
11.8 bcd
12.0 cd
0.5 ounce + 0.2 ounce
4.0 cd
2.5 d
1.5 d
13. Chipco Signature 80WDG
14. Velista 50WDG + Daconil Ultrex 82.5WDG
15. Velista 50WDG + Banner MAXX 1.3ME
16. Velista 50WDG+ Heritage 50WDG
17. Velista 50WDG
18. Torque 3.6SC + Affirm 11.3WDG
19. Secure 4.17SC
0.5 ounce
5.0 bcd
10.5 bcd
13.0 cd
0.6 fluid ounce + 0.9 ounce
1.3 cd
1.5 d
2.0 d
0.5 fluid ounce
29.0 a-d
32.5 abc
33.8 a-d
Curative treatments applied April 25, 2011
20. ProStar 70WP
2.2 ounces
25.8 a-d
19.5 a-d
15.9 cd
21. Affirm 11.3WDG
0.9 ounce
22.0 a-d
13.5 bcd
11.5 cd
22. Heritage TL 0.8ME
2.0 fluid ounces
30.5 a-d
8.0 bcd
9.0 cd
23. Banner MAXX 1.3ME
2.0 fluid ounces
18.0 a-d
18.5 a-d
21.3 bcd
24. Cleary 3336 4FL
4.0 fluid ounces
27.5 a-d
36.3 ab
51.5 ab
3.25 ounces
31.5 a-d
25.0 a-d
23.5 a-d
26. Chipco 26GT 2SC
4.0 fluid ounces
26.5 a-d
25.8 a-d
27.0 a-d
27. Tartan 2.4SC
2.0 fluid ounces
45.3 a
29.8 a-d
26.5 a-d
0.5 ounce
17.8 a-d
9.5 bcd
9.3 cd
25. Daconil Ultrex 82.5WDG
28. Medallion 50WP
29. Chipco Triton Flo 3.1SC
0.75 fluid ounce
33.0 abc
17.8 a-d
16.8 cd
30. Torque 3.6SC
0.9 fluid ounce
28.8 a-d
15.5 bcd
18.0 cd
31. Pentathlon 4LF
10.0 fluid ounces
27.8 a-d
27.5 a-d
35.5 abc
6.0 ounces
22.3 a-d
22.5 a-d
25.0 a-d
0.5 fluid ounce
16.8 a-d
19.0 a-d
26.5 a-d
—
28.8 a-d
46.0 a
52.3 ab
32. Chipco Signature 80WDG
33. Secure 4.17SC
34. Not treated
†
Percent plot area blighted by brown ring patch was rated on a scale of 0%-100%, where 0 = no disease and 100 = entire plot area blighted.
Means followed by the same letter are not signifcantly different from one another. Means were separated using Tukey’s HSD test, P = 0.05.
‡
Table 3. Impact of preventive and curative fungicide applications on brown ring patch disease on a predominantly annual bluegrass putting green at Fiddlers Elbow Country Club,
Bedminster, N.J., 2011.
03.14 GOLF COURSE MANAGEMENT
89
many commonly used turfgrass fungicides as
possible in this study.
Curative fungicide trial, 2013
Treatment No./name†
Rate/1,000 square feet
% brown ring patch (2013)§
April 25
May 1
May 15
1. Headway 1.39ME
3.0 fluid ounces
9.5a‡
3.8b
0.0b
2. Briskway 2.7SC
0.5 fluid ounce
9.5a
5.8b
0.0b
3. Briskway 2.7SC
0.725 fluid ounce
10.0a
2.3b
0.0b
4. HeritageTL 0.8ME
2.0 fluid ounces
7.0a
3.3b
0.0b
5. Medallion 1SC
2.0 fluid ounces
10.0a
2.0b
0.0b
6.8a
20.5a
11.0a
6. Not treated
†
Treatments were applied on April 25 and May 9, 2013.
Means followed by same letter are not signifcantly different. Means were separated using Tukey’s HSD test, P = 0.05.
Percent brown ring patch was rated on a 0-100% scale, where 0 = no disease and 100 = entire plot area blighted.
‡
§
Table 4. Brown ring patch as affected by curative fungicide applications on a predominantly annual bluegrass putting
green in Boyertown, Pa., 2013.
riod, but no treatments provided complete
control. On April 16 (8 days after application), there were no signifcant differences
between treated and untreated plots (Table
2). By April 28 (20 days after application),
only plots treated with Heritage TL (azoxystrobin, Syngenta) had less brown ring patch
than the untreated control. Disease severity
peaked (35% turf area affected) on May 7.
On that date, all treatments, except Banner
MAXX (propiconazole, Syngenta), Endorse
(polyoxin-D, Arysta), and Daconil Ultrex
(chlorothalonil, Syngenta), exhibited reduced disease severity compared to untreated
turf. However, only Heritage TL provided
acceptable control (<5% disease severity) by
the end of the study.
Met ods specifc to t e 2011 effcacy study
Preventive treatments were initiated on
March 22 and were reapplied on April 11
and 25. Curative treatments were applied
once (April 25) when there was 18% to 33%
brown ring patch present and were therefore
considered “late-curative” (rescue) treatments. The entire green was treated with
Embark TO for annual bluegrass seedhead
suppression in mid-April at the label rate.
2011 preventive fungicide results
Symptoms initially appeared on April 11
as orange-yellow to brown rings, 0.5-2 inches
(1.3-5 centimeters) in width, and eventually
ranged from 3 inches to 2 feet (7.6-61 centimeters) in diameter. Data representing the
impact of preventive and curative fungicide
90
GOLF COURSE MANAGEMENT 03.14
treatments on brown ring patch are presented
in Table 3. No fungicide treatments provided
complete control of brown ring patch, due to
the severity of the disease epidemic.
Brown ring patch severity peaked in this
trial on May 11 at 52% turf area affected following a period of cool, humid and overcast
weather. Turf receiving preventive fungicide
treatments typically had signifcantly less
brown ring patch than the untreated control, but this was not the case for most of
the curative treatments. Preventive fungicide
treatments that provided acceptable disease
control throughout the study included Affrm (polyoxin-D, Cleary/Nufarm); Chipco
Triton Flo (triticonazole, Bayer); Heritage
TL; Medallion (fudioxonil, Syngenta); and
Prostar (futolanil, Bayer); as well as tank
mixtures of Torque (tebuconazole, Cleary/
Nufarm) + Affrm; and Velista + Heritage.
Preventive treatments that had the highest levels of disease (that is, disease severity
equivalent to the untreated control) were:
Chipco 26GT (iprodione, Bayer); Chipco
Signature (Aluminum-tris, Bayer); Cleary
3336 (thiophanate-methyl, Cleary/Nufarm);
and Secure. From this study, it was apparent that, although these fungicides are useful
for controlling other turfgrass diseases, they
should not be used alone where brown ring
patch pressure is high. It should also be noted
that some of the fungicides in this study were
not labeled for the control of brown ring
patch and therefore were not expected to
suppress this disease, but we felt it important
to assess the disease suppressive activity of as
2011 curative fungicide summary
No curative treatments provided acceptable control of this disease (<5% turf area
infected), presumably due to the severity of
the epidemic, the late timing of the curative
treatments and the fact that only one application was made after symptoms appeared on
April 11.
While the level of curative brown ring
patch control in this trial was generally fair
to poor (8% to 52% turf area blighted), Affrm, Heritage TL, Medallion and Torque
had signifcantly less disease than untreated
turf on the majority of the rating dates. It’s
important to note that disease severity of
turf treated with late-curative applications of
Banner MAXX, Cleary 3336, Chipco 26GT,
Chipco Signature, Daconil Ultrex, Pentathlon (mancozeb, SePRO), Secure or Tartan
was equivalent to the untreated control.
Therefore, as previously mentioned, such
fungicides should not be relied on as standalone treatments, especially when brown ring
patch is present.
Met ods specifc to t e 2013 effcacy study
An additional curative feld trial was conducted in 2013 on an annual bluegrass research green located in Boyertown, Pa. Treatments were applied on April 25 and May 9
using the methods previously described for
our 2010 and 2011 fungicide trials. The site
was treated with Primo MAXX at (5 fuid
ounces/acre [0.365 liter/hectare]) every 14
days from April 25 throughout the duration
of the trial. Turf was mowed at 0.125 inch
(3.2 millimeters) fve days per week with a
Toro Flex 21 hand-reel mower. Disease severity was assessed (pre- and post-treatment)
as percent turf area blighted by brown ring
patch using the methods previously described
for our 2010 and 2011 trials. Disease control
was considered commercially acceptable if
less than 5% of the turf area was blighted.
The 2013 trial included two pre-mixed
fungicides that were not included in our 2011
study — Briskway (azoxystrobin + difenoconazole; Syngenta) and Headway (azoxystrobin
+ propiconazole; Syngenta) — and were compared to Medallion as well as Heritage TL,
which, in our 2010 and 2011 trials, had proven
to be effective when applied on a curative basis.
Following the completion of our trials, we saw a greening response in areas that had been severely blighted. This symptom is likely due to a breakdown
of organic matter (thatch) and a release of nitrogen and other nutrients resulting in enhanced greening that could be confused with Type II fairy rings.
2013 curative fungicide summary
The treatments were initiated on April 25
when brown ring patch was evenly dispersed
throughout the study (7% to 10% disease),
and there were no differences among the
plots (Table 4). By May 1, all treatments
reduced brown ring patch compared to the
non-treated control (21% turf area infected).
Brown ring patch severity decreased in untreated turf after May 1 with the onset of
warmer air temperatures and, by May 15,
complete control was observed for all fungicide treatments. Brown ring patch severity was moderate in this trial (7% to 21% in
untreated turf). The data indicated that all
of the fungicides tested (Briskway, Headway,
Medallion SC and Heritage TL) provided acceptable disease when applied twice on a curative basis under moderate disease pressure.
Annual bluegrass growing in the aerifcation holes from the previous autumn was seemingly unaffected by brown ring
patch. This could be due to several reasons, but less organic matter and improved turf quality are likely two factors.
92
GOLF COURSE MANAGEMENT 03.14
Fungicide suggestions for the
management of brown ring patch
To our knowledge, the 2011 trial reported
here is the frst to evaluate a broad range of
fungicide chemistries commonly available in
the turfgrass market for both preventive and
curative control of brown ring patch. These
data confrm previous research showing that
fungicides such as Affrm, Heritage, Medallion
and ProStar, which are known to be effective
against other R izoctonia diseases, also provide
high levels of brown ring patch control (2).
Briskway and Headway are pre-mixed fungicides that contain a DMI (difenoconazole and
propiconazole, respectively) combined with
azoxystrobin (the active ingredient in Heritage
TL). Our data from 2013 indicate that these
pre-mixes are as effective as Heritage for the
control of this disease when applied curatively
under moderate disease pressure.
Post-application irrigation and
efficacy of curative fungicide
treatments, 2011
Two of the most effective fungicides in
our 2011 trial, representing two different
chemical classes, were selected to evaluate
the effect of post-treatment irrigation on curative control of brown ring patch. Heritage
TL (2 fuid ounces/1,000 square feet [0.64
milliliter/square meter]) and Chipco Triton Flo (0.75 fuid ounce/1,000 square feet
[0.24 milliliter/square meter]) were applied
once curatively on April 25. The study was
arranged as a split-plot design (each plot had
an irrigated and non-irrigated half) with
four replications. Water (0.15 inch [3.81 millimeters]) was supplied to the irrigated half
of each plot immediately following fungicide
application (within 5 minutes) using a watering can.
Post-application irrigation improved
brown ring patch control on turf treated with
Chipco Triton Flo, but not Heritage TL (data
not shown). Although these results are informative and suggest that post-treatment irrigation may improve brown ring patch control
for some fungicide chemistries, additional research is needed before defnitive statements
can be made since only two products were
evaluated for one year in this small pilot study.
Additional field observations
Where brown ring patch was severe in
our trials, a signifcant degradation of thatch
occurred (visual observations), especially in
untreated plots. Following the completion of
our trials, we also saw a greening response in
areas that had been severely blighted. This
has previously been reported (6) and is shown
All PGR treatments resulted in better turfgrass quality when compared to the untreated control (data not shown). In the plots
where seedheads were suppressed, turf remained a dark green color, and ball roll would likely have been more uniform.
in the photo. This symptom is likely due to
a breakdown of organic matter (thatch) and
a release of nitrogen and other nutrients resulting in enhanced greening that could be
confused with Type II fairy rings (dark green
stimulated turf in a circular patch). Fungicide applications targeting these fairy ringlike symptoms would likely have no effect if
the patches were caused by brown ring patch.
Another interesting feld observation was that
annual bluegrass growing in the aerifcation
holes from the previous autumn was seemingly unaffected by brown ring patch. This
could possibly be due to deeper rooting in the
aerifcation holes resulting in improved plant
health or because fertilizer had collected in
these areas and enhanced turf vigor. It is apparent from this observation that further research is needed to determine the impact of
aerifcation and rooting on brown ring patch.
Effect of spring applications of
PGRs on disease severity, 2012
This small trial was conducted on the same
putting green at Fiddlers Elbow Country Club
as our 2010 and 2011 fungicide trials, but in
03.14 GOLF COURSE MANAGEMENT
93
a different quadrant of the green. The PGRs
Primo MAXX (5 fuid ounces/acre [0.365
liter/hectare]), Proxy (217.8 fuid ounces/
acre [15.9 liters/acre]), Primo (5 fuid ounces/
acre) + Proxy (217.8 fuid ounces/acre), and
Embark (22 fuid ounces/acre [1.6 liters/hectare]) were evaluated for their effect on brown
ring patch and seedheads, in comparison to
an untreated control, at early spring application timings and rates typically used on golf
courses throughout the Northeast. All treatments were applied on March 20 and April 5,
2012, and turf was maintained as described in
our 2011 fungicide effcacy study above. This
trial did not receive applications of any other
PGR or fungicide treatments in spring 2012.
All PGR treatments resulted in better
turfgrass quality when compared to the untreated control (data not shown). This was
primarily due to increased seedhead formation on untreated turf resulting in a whitish-brown color that lowered visual quality
estimates. Embark, Proxy alone and Primo
+ Proxy treatments reduced seedheads compared to untreated and Primo-treated turf
on the majority of rating dates in this study
(data not shown). In the plots where seed-
RESEARCH SAYS
• Limited data are available on the effect of preventive versus curative fungicide applications, posttreatment irrigation and PGR use on the severity
of brown ring patch.
• Preventive fungicides that provided acceptable
disease control included Affirm, Chipco Triton
Flo, Heritage TL, Medallion and Prostar, as well
as tank mixtures of Torque + Affirm and Velista
+ Heritage.
• Curative fungicide treatments did not always
provide acceptable control of brown ring patch.
• Post-application irrigation appeared to improve
curative disease control when Chipco Triton
Flo (but not Heritage TL) was applied, and turf
treated with Proxy + Primo had greater brown
ring patch severity than the untreated control;
however, additional research is needed to
confirm these observations and to more fully understand the impact of post-treatment irrigation
and PGRs on this disease.
94
GOLF COURSE MANAGEMENT 03.14
heads were suppressed, turf remained a dark
green color, and ball roll would likely have
been more uniform.
Although all PGRs in this study except
Proxy alone exhibited “numerically” more
brown ring patch (greater disease severity)
than untreated turf, only turf treated with
Proxy + Primo had signifcantly more disease than the untreated control on one rating date (data not shown). These data suggest that PGR treatments that provide a high
level of annual bluegrass seedhead and foliar
growth suppression during spring may intensify brown ring patch disease on annual
bluegrass putting greens. However, since this
study was only conducted for one year, additional research is needed before this theory
can be confrmed.
Integrated management of brown
ring patch
Brown ring patch is a unique turfgrass
disease that does not respond to management
and environmental conditions in the same
way as other diseases caused by R izoctonia.
Historically, many R izoctonia diseases of
cool-season turf have been associated with
high levels of fertility and are not known to
be affected by PGRs (3). Brown ring patch
thrives under a wide range of temperatures
that, in some regions, can be present from
March through November. Our observation
that turf in aerifcation holes was less affected
by this disease confrms some previous reports suggesting that the amount of thatch,
organic matter and compaction may play a
role in disease severity and control (3).
Superintendents should realize that maintaining greens under conditions of low nitrogen fertility and aggressive PGR use (high
rates and/or short application intervals) to enhance playability may lead to enhanced disease pressure and an increased reliance on fungicides to manage brown ring patch on annual
bluegrass greens. Therefore, when environmental conditions favor disease development,
less aggressive PGR use — as well as adequate
irrigation, nitrogen fertility and fungicide applications — should be used to reduce the potential for severe brown ring patch epidemics.
If PGRs are being used to suppress seedheads in early spring and the course has had
a history of this disease, it would be prudent
to make preventive applications of one of
the fungicides found to be effective in this
and other studies. Since fungicides are still
strongly relied on for brown ring patch management, selection of effective products is important because many of the fungicides commonly used on golf courses are not effective
against this disease. Moreover, if brown ring
patch becomes active, superintendents should
not expect rapid symptom remission because
research has shown that it typically takes
14-21 days or more for signifcant recovery
to occur. Repeated fungicide applications on
a 14-day interval and increased nitrogen applications will aid in recovery if conditions remain conducive for disease development.
Acknowledgments
We thank Fiddlers Elbow Country Club
for the space and fexibility to conduct these
trials on greens that remained in-play for the
duration of the trials. We also thank Bayer,
BASF, Cleary/Nufarm, DuPont, PBI-Gordon, SePRO and Syngenta for providing
product and support for these trials.
Literature cited
1. Dernoeden, P.H. 2013. Creeping Bentgrass Management. 2nd ed. CRC Press, Boca Raton, Fla.
2. McDonald, S.J., D. Settle, L. Stowell et al. 2009.
Chemical control of brown ring patch. Golf Course
Management 77(8):82-88.
3. Smiley, R.W., P.H. Dernoeden and B.B. Clarke. 2005.
Compendium of Turfgrass Diseases. 3rd ed. APS
Press, St. Paul, Minn.
4. Toda, T., T. Mushika, T. Hayakawa et al. 2005.
Brown ring patch: A new disease on bentgrass
caused by Waitea circinata var. circinata. Plant Disease 89:536-542.
5. Wong, F.P., C. Chen and L. Stowell. 2009. Effects of
nitrogen and Primo MAXX on brown ring patch development. Golf Course Management 77(5):117-121.
6. Wong, F.P., and J.E. Kaminski. 2007 A new Rhizoctonia disease of bluegrass putting greens. Golf Course
Management 75(9):98-103.
Steven McDonald ([email protected])
is the founder of Turfgrass Disease Solutions LLC, Spring
City, Pa., and an instructor in the Professional Golf Turf
Program at Rutgers University. Richard Grala is a senior
feld technician with Turfgrass Disease Solutions LLC.
Bruce Clarke is the director of the Rutgers Center for Turfgrass Science and chairman of the department of plant
biology and pathology and a 2014 recipient of GCSAA’s
Col. John Morley Distinguished Service Award.